This application is based on and incorporates herein by reference Japanese patent applications No. 2000-45144 filed Feb. 17, 2000, No. 2000-106993 filed Apr. 7, 2000, and No. 2001-16048, filed Jan. 24, 2001.
The present invention relates to a discharge lamp lighting device that lights up a high voltage discharge lamp used in a vehicle headlight unit or the like. The present invention further relates to a mounting structure for mounting the discharge lamp lighting device onto the vehicle headlight unit or the like.
A discharge lamp lighting device has been used in a vehicle headlight unit. For instance, the discharge lamp lighting device can be mounted outside or inside of the headlight unit. In the case of mounting the discharge lamp lighting device outside of the headlight unit, the discharge lamp is connected to the discharge lamp lighting device via an output electric line extending out from the discharge lamp lighting device and also via a connector that is connected to the output electric line. In the case of mounting the discharge lamp lighting device inside of the headlight unit, the discharge lamp is connected to the discharge lamp lighting device also via the output electric line extending out from the discharge lamp lighting device and via the connector.
However, in both cases, the electric line extending out from the discharge lamp lighting device is required to connect the discharge lamp to the discharge lamp lighting device, and thus a size of the entire device can not be reduced.
To overcome these disadvantages, it has been proposed to accommodate the connector in the discharge lamp lighting device and directly connect the discharge lamp to the connector.
In this case, if the discharge lamp lighting device is mounted near the discharge lamp, the discharge lamp lighting device receives heat conducted or radiated from the discharge lamp. Thus, an internal temperature of the discharge lamp lighting device rises, causing excessive thermal stress on elements in the discharge lamp lighting device.
Thus, it is an objective of the present invention to reduce transmission of heat from a discharge lamp, which is directly connected to a connector accommodated in a discharge lamp lighting device, to the discharge lamp lighting device through heat conduction or heat radiation to reduce thermal stress on the discharge lamp lighting device.
It is another objective of the present invention to reduce transmission of heat to the discharge lamp lighting device from a holder that is provided for securing the discharge lamp to a reflector and that receives heat transmitted from the discharge lamp.
To achieve the objectives of the present invention, in a mounting structure for mounting a discharge lamp lighting device, a holding member for holding a discharge lamp is separated from a securing member for securing the discharge lamp lighting device to a headlight unit or to components in the headlight unit. The holder may have a holder opening for receiving the discharge lamp. Furthermore, the holder may have a holder securing portion for securing the discharge lamp to the headlight unit or to the component in the headlight unit. The holder securing portion can be offset from an area above the holder opening. Also, the securing member can be offset from an area above a connector of the discharge lamp lighting device to which the discharge lamp is connected. In addition, the headlight unit may have a reflector having a plurality of retaining portions. The holder securing portion of the holder and the securing member can be secured to different retaining portions of the reflector.
Furthermore, to achieve the objective of the present invention, a space can be formed between an outer wall surface of the discharge lamp and a connector housing of the connector. Another space can be formed around the connector housing.